The present invention provides a method for the preparation of novel compositions containing strongly antigenic tumor-specific substances and cancer diagnostic methods utilizing said substances and compositions.
It is known that several human cancers such as melanomas, breast or colon cancer possess weakly antigenic tumor-specific substances on the membranes of their composing tumor cells. With the usual methods for extraction and ultracentrifugation, these tumor-specific antigens sometimes referred to in the literature as TSTA's and herein referred to as "TSAs," prove to be even weaker antigens than when in their native association with malignant tumor cells, see K. Sikora et al's article "Purification of Tumor-Specific Transplantation Antigens from Methylcholantrene-Induced Murine Sarcomas by Immobilized Lectins," British J. Cancer 40:831-838, (1979). There is a recent report on sensitization of circulating lymphocytes of women with breast cancers to breast cancer TSAs, see Wm. G. Ramey et al.'s article "Detection of Breast-Tumor Antigen-Sensitive Circulating T-Lymphocytes by Antigen-Stimulated Active Rosette Formation," Cancer Research 39:4796-4801, (1979). This effect may be due to persistent release of breast TSAs of weak antigenicity into the circulation, see G. Currie's "Immunological Aspects of Host Resistance to the Development and Growth of Cancer," Biochimica & Biophys. Acta 458: pp. 154-155, 1976. Because of the weak antigenicity of known TSAs, it has not been possible to establish reliable diagnostic tests for cancer using the TSAs, nor has it been possible to develop therapeutic means utilizing TSAs.
It is known that when lymphocytes sensitized by strong antigens, e.g. Bacillus Calmette-Guerin (BCG), on recontacting the strong sensitizing antigen in vivo or in vitro, macrophages present at the site of reaction may fuse and form multinucleated giant cells, see A. H. Warfel's article "Macrophage Fusion and Multinucleated Giant Cell Formation, Surface Morphology," Experimental & Molecular Pathology 28:163-176 (1978). TSAs obtained from cancer cells are, as noted, weak antigens and when such weak TSAs are contacted with lymphocytes in the presence of macrophages, no macrophage fusion reaction occurs in vivo or in vitro. Conventional heat treatments have been reported to raise to some degree the inherently weak immunogenicity of tumor cells, but the immunologic change was found to be inferior to that produced by X-rays., see H. D. Suit et al.'s article "Immunogenicity of Tumor Cells Inactivated by Heat," Cancer Research 37:3836-3837 (1977). TSAs after conventional heating, while somewhat more active than TSAs produced without heating, are not sufficiently activated to produce specific histologic or in vitro reactions such as the macrophage fusion reaction.
All publications referred to are incorporated herein by this reference.
It is an object of the invention to produce compositions containing TSAs having strong antigenic activity and further to utilize such strongly antigenic TSAs in methods for testing for cancer, and for therapeutic uses.